Two-piece projectile and method of sealing same



United States Patent Inventor Appl. No.

Filed Patented Assignee Jack Brothers Succasunna, NJ.

May 29, 1 968 Dec. 15, 1970 The United States of America as represented by the Secretary of the Army TWO-PIECE PROJECTILE AND METHOD OF SEALING SAME 3 Claims, 4 Drawing Figs.

US. Cl. l02/92.4

Int. Cl. F42b 11/00 Field of Search 102/93, 94, 56, 92.4

[56] References Cited UNITED STATES PATENTS 443,101 12/1890 Maxim 102/93 707,135 8/1902 Maxim 102/93 2,715,874 8/1955 Hablutzel et al..,. 102/93 3,208,345 9/1965 Thompson 102/94X Primary Examiner Robert F. Stahl Attorneys-Harry M. Saragovitz. Edward J. Kelly. Herbert Berl and S. Dubroff PATENTED am 51970 3547;036

SHEET 1 [JP 2 INVENTOR JACK BROTHERS \M A B 52%,!

ATTORNEYS TWO-PIECE PROJECTILE AND METHOD OF SEALING SAME The invention described herein may be manufactured, used, and licensed by or for the U.S. Government for governmental purposes without the payment to me of any royalty thereon.

The present invention relates to'the method of sealing the inside of a container from tremendous pressures existing in an ambient atmosphere when the container has a wall made up of two sections joined together.

The present invention solves the problem of sealing the inside of the container from tremendous pressures by providing a method which is simple, easily adaptable to projectile design and operating on the principle that a high pressure can be sealed out best by a higher pressure opposing it.

Such a problem may exist when a projectile is fired from a gun. The chamber pressures generated by the burning of the propellant therein, may reach as much as 40,000 pounds per square inch, whereas pressures inside a projectile may be 15 pounds per square inch if sealed at atmospheric pressure. Thus, if the joint is not capable of sealing out the 40,000 pounds per square inch, the hot gases may enter the projectile through the joint and function to ignite the pyrotechnic or explosive contents prematurely.

In the past, many ways were tried in attempting to solve the aforementioned problem, namely soldering, brazing, welding, screw threads, liquid sealing compounds which solidified after being applied, and fiber or metallic gaskets. Combinations of several of these were also tried. These methods are unsatisfactory because the tremendous pressures and heat melted the seals or disintegrated them allowing the gases to leak through. Pore holes in the seals, which were weak spots, could not be completely eliminated from soldering, brazing, welding or liquid sealants, and undetectable weak spots caved in under the high pressures.

It is therefore an object of the present invention to provide a method for sealing a two piece projectile or the like which is simple and easily adaptable to projectile design.

A further object is to provide a method of sealing a twopiece projectile or the like which seal will not melt, disintegrate or break down under the tremendous pressures.

A further object is to provide a method of sealing a twopiece projectile or the like which seal eliminates pore holes and undetectable weak spots.

The above objects as well as others together with the benefits and advantages of the invention will be apparent upon reference to the detailed description set forth below, particularly when taken in conjunction with the drawings annexed hereto in which:

FIG. ll illustrates the two portions of a projectile before they are joined together.

FIG. 2 and FIG. 3 illustrate the progression of two portions of a projectile being joined together.

FIG. 4 illustrates the two portions of a projectile completely joined together.

Referring first to FIG. 1, there is shown a portion of a projectile body 10. having screw threads 12 which communicate with a screw thread 34 of a projectile base T6 The projectile body 10 is generally hollow and carries a payload, not shown.

The projectile base 16 is the rear portion of the projectile, and is attached to the projectile body 10 thereby making a hollow container. The attaching screw threads l2 and 14 provide the linear pressures necessary for proper operation of the invention. Integral with the body 10 is a cylindrical extension 18 which is constructed to cooperate with a cylindrical recess 20 integral with said base portion 16. An elastic sealing material 22 such as Teflon," rubber or other'elastic plastic, is provided in the recess 20. A rigid sealing material 24 is placed in position adjacent the recess 20, as seen in FIG. 1. It is intended that the extension 18 will punch out a cylindrical ring 26 as seen in FIGS. 3 and 4 from the rigid sealing material 24. As

can be seen in FIG. 2 as the projectile body 10 is screwthreaded onto the projectile base 16, the extension 18 pushes part of the rigid sealing material 24, as at 26, into the recess Turning now to FIG. 3, it can be seen that as the extension l8 continues into the recess 20 the portion of the rigid sealing material 26, contacted by said extension, compresses the elastic sealing material 22.

The view, as seen in FIG. 4 illustrates the projectile body it) completely screw-threaded to the projectile base 16 causing elastic sealing material 22 to be completely compressed in recess 20 and held there by the portion 26 of the rigid sealing material and also the remainder of the rigid sealing material secured between the projectile body 10 and the projectile base 16.

The aforementioned method provides a simple, effective, economical seal without pore holes that might leak under very high pressures. The fit between threads in the joint is automatically taken up by the elastic seal during and after setback whereas a fiber or metallic gasket would take a new set and leak.

Extension and recess members may be reversed in their relationship, and pressure to punch and seal may be applied by sources other than the attaching threads. The rigid sealing material may be attached to the extension either permanently or temporarily before the sealing ring is punched out.

In determining the amounts of pressure necessary in a particular situation, it is important to know the amount of internal pressure that will be involved. For example if the seal is applied to a projectile, as illustrated, and if for every .010 inches that the elastic sealing material is compressed, 5000 pounds per square inch pressure has to be applied, and if the joint is going to be subjected to 40,000 p.s.i. pressure, then, to provide a safety factor it is necessary to compress the elastic sealing material to pressure of 50,000 p.s.i. The two parts are therefore screwed together until the elastic sealing material has been compressed 0.1 inch. The projectile is then prepared for firing, and to be subjected to 40,000 p.s.i. Setback further compresses the elastic sealing material because the thread fit permits movement between the body and the base. However, when setback decays, the elastic sealing material relaxes to its original 50,000 p.s.i. pressure effectively sealing out the 40,000 p.s.i. pressure under all conditions.

Obviously, many modifications andv'ariations of the present invention are possible in light of the above teachings. It is therefore to be understood, that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

I claim:

1. A method of sealing a two-piece projectile having screw threads on each piece, including the steps of:

providing one piece of said projectile with a cylindrical extension adjacent the end of its screw thread;

providing the other piece of said projectile with a cylindrical recess adjacent the end of its screw thread;

placing an elastic sealing material in said recess;

overlapping said recess with rigid sealing material; and

screwing said one piece into said other piece so as to cause said extension to push part of said rigid sealing material into said recess while compressing said elastic sealing material.

2. A two piece projectile comprising:

screw threads on each piece;

a cylindrical extension adjacent the end of one piece;

a cylindrical recess adjacent the end of the other piece which upon the screwing of the two pieces together will accept said extension therein;

an elastic sealing material within said recess; and

rigid sealing material juxtaposed within said recess between the elastic sealing material and the cylindrical extension.

3. A method as described in claim I! wherein said elastic sealing material is selected from the group consisting of Teflon and rubber. 

